Permanent magnet alternators are widely used for a variety of battery ignition systems. In many of these systems, electronic voltage regulators are provided for small engines and must be economical to manufacture while being reliable in operation. These regulators usually provide some type of protective circuitry to prevent damage to the electronic components which could result if no battery is present or is improperly connected.
U.S. Pat. No. 4,146,831 discloses a regulated rectifier for an alternator battery charging system. The regulator of this patent includes a full wave bridge rectifier having a pair of silicon controlled rectifiers (SCRs) selectively rendered conductor to charge the battery with the output of the bridge rectifier whenever the battery voltage drops below a predetermined level. The patented circuit includes a pair of transistors connected for tandem operation, one to sense the battery voltage level and the other to be turned "on" thereby and to gate "on" the SCRs in the rectifier bridge.
It is the principal object of this invention to provide an improved electronic regulator for a battery charging system which, as compared to prior systems, is more reliable and provides greater circuit protection against high current flow resulting from either no battery load, improper battery connection or faulty battery operation.
Another object of this invention is to provide an electronic regulator of the above type in which protection is provided for its components against a sulfated battery being present in the system.